Table Inheritance and dropped columns

Hello,

I'm trying to figure out if this is a bug or a feature.

Two child tables, one created with inheritance, one altered to have
inheritance:

create table A(a text, b text);
create table A1() inherits (A);
create table A2(a text, b text);
alter table A2 INHERIT A;

When you drop a column from the parent table only the tables CREATED with
inheritance drop the column:

alter table A drop column b;

\d A1
Column | Type | Modifiers
--------+------+-----------
a | text |
Inherits: a

\d A2
Column | Type | Modifiers
--------+------+-----------
a | text |
b | text |
Inherits: a

Is this intended behavior? I have postgres 8.2.9.

-Caleb